import java.util.*;
public class Iterator
{
	public static void main(String [] args)
	{
		Collection c=new HashSet();
		c.add("chenxin");
		c.add("shichaoya");
		//Iterator i=c.iterator();
		while(c.iterator().hasNext())
		{
			System.out.println(c.iterator().next());
		}
	}
}